iMac will not startup!

I have a very very serious problem with my iMac, it will not boot OS X at all, it won't even make the startup noise! I was just starting to install Windows XP (I was up to the part where you need to agree to the license agreement) on it when it just shut off for no reason. When I turned the iMac back on it did nothing, just stayed on the grey screen, I didn't even get the startup noise. So I got the Windows XP install disc out of it and have tried everything I can think from trying to do a hardware test (would not work) to trying to reinstall OS X (obversely did not work) of to start OS X up but nothing will work. Does anyone know what else I could do or will I have to send it away to Apple to get this problem fixed?

I have not tried option yet but I have tried using install disc one and holding C, nothing happened. When I hold X it goes to a black screen with a small white bar (around 5 pixels long and two high) in the upper left middle of the screen. Command+option+P+R does not help, nothing is helping! I can not ring Apple support as it is after hours as well.

Ok, everything is working fine (just finished updating to 10.4.8) and I would even say it is working better now, everything seems to be so quick.

I am a little pissed that I lost all my data but luckly I had only has the computer 2 months so I did not loose anything too important. Hopefully that will be my first and last bad experiance with this Mac.

Ihave the same : grey screen and nothing else. I tried to open the Open firmware /option+command+o+f/ but it not works. You have at last a CD icon whe You push the alt button - When I push the alt button at start I have only a mouse cursor - nothing else.No icons.....I can't reinstall system I can't start it....

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